Psoriasis is a long-term immune-mediated condition in which skin cells are produced far faster than usual and inflammation accompanies that turnover. It shows on the skin, but it is understood as a condition of the immune system, which is why it is associated with effects elsewhere in the body.
What is actually happening in the skin?
Skin renews itself continuously. Cells are made in the lower epidermis, mature as they rise, and are eventually shed from the surface, a journey that normally takes several weeks.
In psoriasis that journey is compressed dramatically. Immune signalling drives the cells to divide and travel much faster, so they arrive at the surface before they have properly matured and before the cells ahead of them have been shed. What accumulates is the thickened, scaly plaque that characterises the condition. Underneath, small blood vessels are dilated and the tissue is inflamed, which is why plaques are often warm and why the skin beneath the scale is red.
The immune activity is the primary event. Skin appearance is downstream of it. That ordering sounds like a technicality and it is the single most consequential thing to understand about the condition, because it explains why a dermatologist asks about joints, about general health and about things that seem to have nothing to do with your elbows.
Genetics contribute substantially, and psoriasis frequently runs in families. Psoriasis is not caught, not passed on and not caused by anything anyone did. Certain events are recognised as capable of setting it off or making it flare in someone predisposed, including some infections, some medicines, injury to the skin, and periods of stress.
How would a dermatologist describe it?
A plaque is the raised, well-demarcated area itself, and demarcation is emphasised: psoriasis plaques tend to have distinct borders, which distinguishes them from conditions that fade gradually into surrounding skin.
Scale describes the surface, and in psoriasis it is characteristically silvery and adherent rather than greasy. The Koebner phenomenon is the term for new lesions appearing at sites of skin injury, which is why clinicians ask about scratches, tattoos and surgery.
Distribution is described in patterns. Plaque psoriasis is the most familiar, favouring the outer surfaces of elbows and knees, the scalp and the lower back. Guttate psoriasis describes small drop-shaped lesions appearing widely, often following an infection. Flexural or inverse psoriasis affects skin folds and looks different, with less scale, because of the moisture there. Pustular and erythrodermic forms are less common and are treated as needing prompt assessment.
Nail involvement gets examined specifically. Pitting, thickening and separation of the nail from its bed are recognised features, and their presence is informative beyond the nails themselves.
Psoriatic arthritis is the term for joint involvement. Clinicians ask about it directly rather than waiting for it to be volunteered.
What usually happens at a consultation?
The history is broader than a skin history. Alongside questions about when plaques appeared, where they are, how they behave and what has been tried, expect questions about joints, about your general health, about other medical conditions, about medicines you take and about family history. Some of this bears on which approaches are appropriate, which is why it is asked before anything else is discussed.
The examination usually extends well beyond the area you mention. Scalp, nails, elbows, knees, lower back and skin folds are looked at as a matter of course, because the pattern across sites carries information no single plaque does.
Clinicians also ask about effect on daily life, and the question is not a courtesy. Psoriasis affects sleep, clothing, work and social life in ways that correlate poorly with how extensive it looks, and that assessment forms part of the clinical picture.
What is worth asking?
Ask whether your joints should be assessed, and by whom. Joint involvement is a recognised part of this condition, it is asked about for good reason, and knowing who is responsible for that part saves a great deal of time later.
Ask which pattern the clinician is describing, and which sites are involved. People are frequently surprised to learn that their scalp or nails have been part of the same condition all along, and it changes how you interpret what happens next.
Enquire about what typically prompts a flare in a case like yours. Because recognised triggers include ordinary events such as infections and skin injury, knowing which apply to you is more useful than any general list.
Where the effect on daily life is significant, say so plainly. It is part of the clinical assessment rather than a complaint, and a clinician who does not hear it cannot take it into account.
What this page does not do
It does not tell you whether what is on your skin is psoriasis, nor which form. No treatment is recommended here, no medicine is named, and no dose or schedule appears anywhere on the page, which also carries no commercial content of any kind.
Common questions
Is psoriasis contagious?
No. Nothing about it can be passed to another person by touch or by any other route. It arises from an individual's own immune system, and the persistence of the belief that it might be catching causes a good deal of avoidable distress.
Why is psoriasis described as an immune condition rather than a skin condition?
Because the driving process is immune activity, and the skin is where its effects become visible. That framing matters clinically, since it explains why psoriasis is associated with involvement of the joints and with other health considerations that a clinician will ask about.
Can psoriasis affect the joints?
Joint involvement is a recognised part of the picture for some people with psoriasis, and it is asked about routinely at dermatology appointments for that reason. Mentioning any joint pain, stiffness or swelling is worth doing even when it seems unconnected to your skin.
Does stress cause psoriasis?
Stress is widely reported as influencing the course of psoriasis in people who already have it, rather than as causing the condition. The relationship also runs the other way, since living with visible skin disease is itself stressful, and clinicians generally treat both directions as real.
Does psoriasis ever go away completely?
It is described as a long-term condition that fluctuates, and periods with little or no visible activity are common and can be lengthy. Whether that pattern applies to any individual case is a question for the clinician who has assessed it.
Sources
- Psoriasis — conditions — NHS (United Kingdom) · accessed
- Information and support for people affected by psoriasis — The Psoriasis Association (United Kingdom) · accessed
Last updated . How this page was written.